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Erratic Idle, help!

Discussion in 'A3/S3 Forum (8L Chassis)' started by kelk11, Jul 17, 2013.

  1. kelk11
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    kelk11 Member

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    [Jul 17, 2013]
    So this morning on the way to work I changed gear at about 4000 revs to a loud whoosh/pop noise more aggresive than the usual Dv noise. Since then at low revs it sounds really rough and hunts around at idle nearly stalling before lifting the revs to 1200rpm. there is also a popping noise from the exhaust when coasting.

    Now ive ran vcds lite with no errors recorded, unplugged the maf which made no difference.

    What else can i check? would the dv cause erratic idle if it was damaged?

    Cheers
    #1
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  3. Mikemc
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    Mikemc Scooby Slayer

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    [Jul 17, 2013]
    Possible boost leak, can you hear any noises on boost?
    #2
  4. kelk11
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    kelk11 Member

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    [Jul 17, 2013]
    seems to drive normal above 2500rpm, just rough when its under that.
    #3
  5. Goubo1
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    Goubo1 Active Member

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    [Jul 17, 2013]
    Check under the inlet manifold I had same symptoms on my first s3 and it was a burst hose
    #4
    kelk11 likes this.
  6. kelk11
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    kelk11 Member

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    [Jul 17, 2013]
    ill go take a look but there's not a great deal ill be able to do tonight, reckon its ok to drive until i get it sorted? got a 70mile round trip to make tomorrow, looks like it maybe time for a catch can upgrade and ditch the pcv.
    #5
  7. 16Klappe
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    16Klappe RacecaR forward is RacecaR backwards. Supporter

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    [Jul 17, 2013]
    Unplug the N75 valve until it's sorted, sounds very much boost leaky.

    Popping from the exhaust is plausibly due to running rich.
    #6
  8. kelk11
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    kelk11 Member

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    [Jul 17, 2013]
    cheers Goubo, reckon i've found the offending pipe, pushed it back together and its seems to be holding so ill just take it steady until i can replace it and idle has returned to normal.

    this is what i found

    [​IMG]
    [​IMG]
    [​IMG]
    #7
  9. Goubo1
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    Goubo1 Active Member

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    [Jul 17, 2013]
    good stuff man least you know what it is now :)
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  10. kelk11
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    kelk11 Member

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    [Jul 29, 2013]
    thought id add the outcome to this for anyone who searches the same problem, I've just fitted a catch can and removed the pcv system.

    this section just fell apart

    [​IMG]

    and maybe this split hose haha

    [​IMG]
    #9

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